1. Field of the Invention
Embodiments of the present invention generally relate to a system and method for the detection of plasma excursions, such as arcs, micro-arcs, or other plasma instability, during plasma processing.
2. Description of the Related Art
During plasma processing of substrates, such as plasma etch, plasma enhanced chemical vapor deposition (PECVD), or physical vapor deposition (PVD), plasma excursions, such as arcs, micro-arcs, or other plasma instability, occurs sporadically and unpredictably. In addition, the requirements of certain processes substantially increase the probability of electrical breakdown and plasma excursions. Such plasma excursions result in shifted process results, reduced product yield, and increased system downtime. Thus, detection of plasma excursions during plasma processing of substrates is desired to better define and control process conditions having fewer plasma excursions.
Prior art attempts at detecting plasma excursions, such as arcing, involves measuring the radio frequency (RF) waveform generated at or near an RF power supply far from the processing chamber or between the RF power supply and an RF matching network positioned between the RF power supply and the plasma load of a processing chamber. The RF waveform is typically measured in analog form and digitized, followed by digital signal processing. It has been found that such prior art methods have an overall sampling rate in the millisecond range, which is too slow to detect and resolve arcs or micro-arcs that occur within a few microseconds. It has also been found that prior art plasma excursion detection methods are susceptible to delay and distortion, resulting in poor recognition of a substantial amount of plasma instabilities. Therefore, improved plasma excursion detection apparatus and methods are needed to overcome the shortcoming of the prior art.